1. Field of the Invention
This invention relates to an optical scanner and particularly to an optical scanner that has modular components to facilitate assembly, disassembly and transportation.
2 Description of the Prior Art
Scanner is a widely used computer peripheral device for capturing document image and converting the document image to digital signals for computer process.
FIG. 1 shows a typical conventional optical scanner 10 which generally includes a base 11, a driving means 12, a chassis 13, a document board 14 and a top cover 15.
The base 11 is a rectangular casing with a top opening for housing a circuit board 112, a slide bar 114 and a rail 116 therein. The circuit board 112 generally mates with the chassis 13 to. provide a fixed resolution power and is fixedly mounted in the base 11. The slide bar 114 is a round metal bar having two ends fixedly engaged in the base 11 at one side. The rail 116 is parallel with the slide bar 114 and is located at another side in the case 11. The casing has four side walls each has a plurality of slots 118 formed therein.
The driving means 12 is fixedly mounted in the base 11 and includes a motor 122 and a belt 124 driven by the motor 122. The belt 124 is parallel with the slide bar 114.
The chassis 13 includes mirrors, lens and a charged couple device (CCD, not shown in the figure) for transmitting and receiving document image. The image is converted to signals for transmitting to the circuit board 112 by mean of a flat cable 132. The chassis 13 further has a clamp 134 to engage with the belt 124, a pulley 136 running on the rail 116 and a guiding bore 138 slidably housing the slide bar 114.
The document board 14 is a rectangular board covering the top opening of the base and is transparent in the center for holding a document thereon. The document image may be transmitted to the chassis 13. The document board 14 has side edges which has a plurality of lugs 142 engageable with the slots 118. At one end of the document board 14, a pair of spaced pivot shafts 144 are provided.
The top cover 15 is a rectangular flat member having two pivot seats 152 at one end engageable with the pivot shafts 144. Under the top cover 15, a white pad (not shown in the figure) is provided to match the transparent portion of the document board 14.
The circuit board 112 usually can process only fixed resolution and is fixedly mounted in the base 11. The chassis 13 has to match with the circuit board 112 for a processing fixed resolution image. For assembly, the guiding bore 138 should engage with the slide bar 114 then mount the side bar 114 in the base 11. The pulley 136 is slidable on the rail 116. The lugs 142 should engage with the slots 118. The aforesaid assembly has the following disadvantages:
a. The scanner 10 is usually sold and delivered by complete unit. It means the assembly and packaging have to be completed before shipment. It is bulky and costs higher. PA1 b. The components are not modularized. It is difficult for production and assembly. PA1 c. It offers only fixed resolution and no casing color selection. PA1 d. It is difficult to disassemble for repairs and maintenance.